Which set of measurements could be the side lengths of a triangle?

a.)3m, 6m, 3m
b.)4m, 7m, 12m
c.)9m, 5m, 3m
d.)4m, 11m, 9m

answer: option c is correct

step-by-step explanation:

we know tha tcos(a-b) = cosa cosb + sinasinb

plugging a = 180 and b = ф

cos(180-ф)= cos180cosф+sin180sinф

                  = (-1) cosф+ (0) sinф   [ since cos180=-1 and sin180 =0]

                  = -cosф + 0

                  = -cosф

therefore option c is the correct answer.        

answer:

140°  

step-by-step explanation:

the reflex angle is the larger of two angles.

reflex + obtuse = 360     set reflex = 220

  220 + obtuse = 360     subtract 220 from each side

            obtuse = 140

answer:

51 percent

(it is actually 51.11, but since you're rounding it will be 51)